Lissandra ult not working on Ezreal [GAMEPLAY]

Since latest patches, AP MID Ezreal is amongst the most common picked champions... As such I m trying to play against him with as many different champions possible, so once i picked my personal best, Lissandra.

Once we reached lvl 6, i went agressive and ulted him, in the exact moment of me ulting him, he started channeling!!! Now comes the important part. Lissandra's ult is a stun, therefore must, MUST, stop channeling spells, movement, attack animations etc. The entire animation of Lissandra's ult went off, he was stunned and the entire circle apeared. so WHILE STUNNED, Ezreal's ult went off. Many would think i havent seen it properly since its a ridiculusly small time gap, BUT, the entire animation of ezreal's movement stopped so should the channel, but stunned as he was, ult went off and hit me.

I played Ezreal long time ago, when i mained adc role, and Ezreal was my main adc to pick. I am very well aware of his timings, animation, how to play him and many stuff more. Also, in this season i prefer playing with Lissandra, so I am also aware of what she does, how the animation goes, time to activate certain spells and so on.

I would like Riot to look up into this, since both champions are strong in this patch and picked so many times. It can be extremely frustrating, when a more skilled player (where at this particular game that may or may not be the case) looses a fight 1v1 only due to a BUG in the game.

Hopefully, Problem with be at least looked into!